This invention relates generally to an internal combustion engine, and more specifically to a method and apparatus for controlling the temperature of combustion (intake) air to the internal combustion engine.
Machines that are powered by internal combustion engines must be capable of operating in a variety of environmental conditions. One such example is operation in extreme temperatures. Additionally, customers and governmental regulations often require the engine to operate at maximum efficiency with minimum pollutant output. Research has shown that most diesel engines operate best when intake air temperature is between 42xc2x0 C. and 48xc2x0 C. (108xc2x0 F. and 118xc2x0 F.). Diesel engines often have turbochargers to increase performance and efficiency. The process of turbo-charging heats the intake air. The amount of heat produced is dependent upon how fast the engine is operating and the amount that the turbocharger is compressing the intake air. At low idle the temperature increase due to turbo-charging may only be 25xc2x0 C. (77xc2x0 F.), while at full load the temperature increase of the intake air may be 125xc2x0 C. (257xc2x0 F.) or more. Because of this temperature increase it is typical provide a method to cool the intake air.
Typical methods of cooling the intake air on a turbo-charged diesel engine are through the use of a separate circuit aftercooler (SCAC) or an air to air aftercooler (ATAC). A SCAC comprises a radiator having two portions (SCAC and jacket water), a SCAC pump, and an aftercooler (air to liquid heat exchanger) located down stream from the turbo-charger. Coolant flows from the SCAC portion of the radiator to the SCAC pump, after the SCAC pump the coolant then flows through the aftercooler to remove heat from the intake air. The heated coolant then flows back to the SCAC portion of the radiator.
During operation of diesel engines in extreme cold temperatures a different problem may occur. If the intake air temperature is below the 42xc2x0 C.-48xc2x0 C. (108xc2x0 F.-118xc2x0 F.) range, poor combustion may occur. When this condition occurs it desirable to pre-heat the intake air. It would additionally be beneficial to provide an automatic system for controlling the temperature of the intake air.
In a first aspect of the present invention a liquid cooled internal combustion engine having a radiator, a jacket water pump, an aftercooler and a fluid control valve. The fluid control valve is moveable between a first position and a second position. In the first position the control valve directs coolant from the jacket water pump to the aftercooler and a jacket water circuit of the engine simultaneously. In the second position the control valve directs coolant to the jacket water circuit first and to the aftercooler second.
In a second aspect of the present invention is a method for controlling the temperature of intake air in an internal combustion engine. The method for controlling the temperature includes providing intake air to an intake air circuit with an aftercooler. Next the temperature of the intake air is determined, if the temperature of the air is below a predetermined value, coolant is directed first through a jacket water circuit and next to the aftercooler. If the temperature is above the predetermined value, coolant is directed simultaneously through the jacket water circuit and the aftercooler.